From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by sourceware.org (Postfix) with ESMTPS id 4EC7E385741C for ; Tue, 17 May 2022 15:40:50 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4EC7E385741C Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 7ADE61F938 for ; Tue, 17 May 2022 15:40:49 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 64B6013AA2 for ; Tue, 17 May 2022 15:40:49 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 8jZgFwHCg2L/eAAAMHmgww (envelope-from ) for ; Tue, 17 May 2022 15:40:49 +0000 From: Tom de Vries To: gdb-patches@sourceware.org Subject: [PATCH 1/2] [gdb/exp] Fix UB in scalar_binop Date: Tue, 17 May 2022 17:40:47 +0200 Message-Id: <20220517154048.13213-1-tdevries@suse.de> X-Mailer: git-send-email 2.35.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-12.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 May 2022 15:40:51 -0000 When building gdb with -fsanitize=undefined, I run into: ... $ gdb -q -batch -ex "p -(-0x7fffffffffffffff - 1)" src/gdb/valarith.c:1385:10: runtime error: signed integer overflow: \ 0 - -9223372036854775808 cannot be represented in type 'long int' $1 = -9223372036854775808 ... Fix this by performing the substraction in scalar_binop using unsigned types. Tested on x86_64-linux. --- gdb/testsuite/gdb.base/arithmet.exp | 2 ++ gdb/valarith.c | 5 ++++- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/gdb/testsuite/gdb.base/arithmet.exp b/gdb/testsuite/gdb.base/arithmet.exp index b6009a36235..4905c2e2706 100644 --- a/gdb/testsuite/gdb.base/arithmet.exp +++ b/gdb/testsuite/gdb.base/arithmet.exp @@ -98,3 +98,5 @@ gdb_test "print x-(y+w)" "3" gdb_test "print x/(y*w)" "0" gdb_test "print x-(y/w)" "9" gdb_test "print (x+y)*w" "42" + +gdb_test "p /x -(-0x7fffffffffffffff - 1)" " = 0x8000000000000000" diff --git a/gdb/valarith.c b/gdb/valarith.c index 6210267826e..526cc02599e 100644 --- a/gdb/valarith.c +++ b/gdb/valarith.c @@ -1382,7 +1382,10 @@ scalar_binop (struct value *arg1, struct value *arg2, enum exp_opcode op) break; case BINOP_SUB: - v = v1 - v2; + /* Avoid runtime error: signed integer overflow: \ + 0 - -9223372036854775808 cannot be represented in type + 'long int'. */ + v = (ULONGEST)v1 - (ULONGEST)v2; break; case BINOP_MUL: base-commit: a1f2ddd38378c8db63e75daa28b7e304c2fd774f -- 2.35.3